Study disputes MHRA warnings over varenicline suicide link

02 Oct 09

The BMJ analysis, led by several MHRA expert advisors, found no clear evidence that varenicline was associated with an increased risk or fatal or non-fatal self harm compared with nicotine replacement therapy or buproprion. In July the MHRA warned varenicline could cause suicidal thoughts and behaviour even in those with no history of pre-existing psychiatric conditions – a claim disputed by some GPs who argued it did not reflect their clinical experience.

The new analysis of data from 80,000 patients in the UK general practice research database between September 2006 and June 2008 identified 166 episodes of non-fatal self harm and two suicides – both in patients prescribed NRT.

The incidence of fatal or non-fatal self harm was 533.1 per 100,00 person-years in patients prescribed varenicline, 498.7 for buproprion and 751.1 for NRT products.

But researchers said although the hazard ratios suggested people prescribed varenicline were 12% more likely to self-harm and 43% more likely to have suicidal thoughts than patients using nicotine replacement products, the wide confidence intervals meant they ‘cannot rule out either a halving or a two-fold increase in risk’.

Study leader Professor David Gunnell, professor of epidemiology at the university of Bristol, also cautioned: ‘The analysis of patients prescribed varenicline suggested they were likely to be at lower risk of self harm than those prescribed nicotine replacement products — they had lower levels of past psychiatric consultation and previous self harm.’

Nevertheless, Professor Gunnell, a member of the MHRA’s pharmacovigilance expert advisory group, insisted the results of the study were ‘reassuring’.

He told Pulse: ‘This is still an important public health issue and the MHRA will consider this evidence.’